Pocket hole issue

[Larry Foster]

I checked around but didn't see this specific question.
So, if you might kindly indulge me....

I was making some cabinets to go under my one bench.
3/4" plywood for the ends and sides and 1/2" for the top, bottom and back.

Because I needed quick and functional and not fine craftsmanship, I just did butt joints with no glue.

I set the drill bit to 3/4 because I thought you drilled the thicker piece.
Tried the 1-1/4" screws and the tip came out.
1" didn't hold well.

I wouldn't consider these joints to be very strong.

Any ideas where I messed up, please?

Thank you.

[Tim Bueler]

You can drill either piece. According to Kreg's chart if you're drilling the 3/4" piece set the jig at 3/4 and use a 1" screw. If you're drilling the 1/2" piece set the jig at 1/2 and use a 1" screw. I'm pretty sure I've drilled the 1/2" piece, with the jig and drill bit both set for 3/4", and used a 1-1/4" screw. Can't remember for sure. Try it on some scrap before you commit.

[Jim Becker]

About that no glue... ;) The glue is where the majority of the strength comes from.

That said, while I find that pocket screws are very effective in 3/4" or thicker material, I find that they are a lot harder to use in 1/2" material because of how little material is there to support the screw head and how easy it is to "scrunch" the material if you inadvertently over-tighten them. For 1/2" plywood, butt joints with glue and #7 trim-head screws in pre-drilled holes/countersinks have worked well for me for my tack trunk commissions, although it's important to note that those joints get covered with thick veneer so the screws are not visible. For your quickie cabinets, you could do the same by putting the 1/2" material on the top, bottom and backs so it overlays the 3/4" sides and screw in from the top, bottom and back into the center of the 3/4" material. It's just as fast as pocket screws, easier to do with the dueling material thicknesses and extremely strong with PVA glue.

[Larry Foster]

Thanks, Tim and Jim.

In my case, haste makes waste.

My shop was only about 40 yesterday when trying to do this so I was hurrying a little.

I'll be doing the drawers today or tomorrow and will definitely use glue.
And plan to use 1/2".
We'll see how this turns out.
:)

[andy bessette]

...making some cabinets to go under my one bench. 3/4" plywood for the ends and sides and 1/2" for the top, bottom and back.
Because I needed quick and functional and not fine craftsmanship, I just did butt joints with no glue...

This is very poor, rather weak construction. Vastly stronger, and extremely simple to build, is to screw and glue the plywood to 3/4"square corner cleats (strips of wood) with the screws going through the plywood and threading into the solid wood strips.

[Jim Dwight]

I built a Paulk style work surface of 1/2 with pocket screws and it came out fine but the screws do poke a bit in places. I glued it so when the glue sets, you can remove any offending screws.

My workbench is all 3/4 with through screws and glue.

I built a bunch of drawers out of nominal 1/2 sides but I stapled them. Crude but with glue it holds up well. For a shop drawer, it would be fine (at least in my shop). I also built a bunch of them out of 3/4 with pocket screws. I dovetailed a bunch too. Biggest issue with the staples is keeping them from coming out the side of the 1/2. Brads and glue would probably hold almost as well and be less trouble.

[Larry Foster]

Thanks, Andy and Jim.

In the end, I may not have saved much time by using pocket holes for this.

[Bill Dufour]

I would throw a few biscuits in just to help keep things aligned while I get the screws in. How cold is too cold for wood glue to work?

[glenn bradley]

Kreg makes a jig and drill bit for thinner stock. I use them for drawer (https://www.amazon.com/Kreg-KJMICRODGB-Micro-Drill-System/dp/B002AKJ2F2/ref=sr_1_4?ie=UTF8&qid=1509420337&sr=8-4&keywords=kreg+mini) boxes here and there and they are fine. If you already have the sleeve (https://www.amazon.com/Kreg-KPDGB-Portable-Drill-Guide/dp/B003Y8XD2W/ref=pd_sim_469_3?_encoding=UTF8&psc=1&refRID=T7D4DCK2BV40NPF23NSA&dpID=41QDuUT6ebL&preST=_SY300_QL70_&dpSrc=detail) from the standard size jig (which I do) then setting depth is a no-brainer.

[Larry Foster]

All those guys on YouTube, like Jay Bates, don't tell you this when they're making their 1/2" drawers

[Jim Becker]

The challenge with 1/2" material is that there is very little tolerance with the drilling...you have to have the depth very precise to get both holding power and to avoid "poke throughs" with the 1" pocket screws. This is definitely a "measure three times, drill once" scenario!

[Larry Foster]

This is definitely a "measure three times, drill once"

:)

Does the 3/4" joining the 1/2" change this?

I'm thinking this should have been one of those times I should have drilled the thinner piece

[Jim Becker]

:)

Does the 3/4" joining the 1/2" change this?

I'm thinking this should have been one of those times I should have drilled the thinner piece

Strictly speaking, the "measure multiple times" thing is a given regardless. But to your specific question, it depend on which thickness the pocket screws are going in, but there is less flexibility when 1/2" material is involved to insure strength without "poke through". Nature of the beast.

[Edwin Santos]

This is definitely a "measure three times, drill once" scenario!


:)

Does the 3/4" joining the 1/2" change this?

I'm thinking this should have been one of those times I should have drilled the thinner piece

Usually the idea is to drill the part that is less exposed. In your case, if I'm understanding it correctly, the 1/2" material is for the cabinet tops and bottoms and back, so yes, I would be drilling the 1/2" material because it's probably less visible anyway. But a general rule when dealing with different thicknesses is to drill the thinner piece and drive the screw into the thicker piece.
The "measure three times" thing could be a little misleading in this case. I think all he means is to take care when setting the depth stop on the drill bit the one time for the job. If you drill the 1/2" material, then the screw has a 1/4" more material for travel in the thicker part. The best thing to do is to drill a joint or two in some identical scrap to dial in the depth setting and ensure no poke through.

[Larry Foster]

Thank you, Edwin.

I drilled the 3/4 piece because they said to always drill the thicker piece except when you don't.
This is one of those exceptions, I think.

The pocket holes were on the insides of the cabinets and would be hidden by the drawers

[Warren Lake]

rabbet the sides for all parts, glue and staple. Nothing shows and its strong. I have melmine shop cabinets that came with a machine here put together with pocket screws probably took just as long or longer to do.

[Larry Foster]

Thanks, Warren.

All of this great advice is for the next time since the carcass is already built and "good enough" for now.
I do have other things that all this information will be helpful.

[Jim Becker]

The "measure three times" thing could be a little misleading in this case. I think all he means is to take care when setting the depth stop on the drill bit the one time for the job. If you drill the 1/2" material, then the screw has a 1/4" more material for travel in the thicker part. The best thing to do is to drill a joint or two in some identical scrap to dial in the depth setting and ensure no poke through.

This is exactly what I was referring to. The drilling depty tolerance with 1/2" material is "really small"...and yea...test with scrap.

[Charles Lent]

Now disassemble your cabinet and put it back together using the pocket hole screws to hold it together "until the glue dries". I have never trusted the holding power of pocket hole screws alone, but they sure speed up a glued together assembly by eliminating the clamps and the need for doing sub-assemblies and waiting several times for the glue on the sub-assemblies to dry before doing the final assembly and glue-up.

Charley

[Larry Foster]

May not be a bad suggestion and one I will definitely consider.
Thanks
As well as drilling through the thinner and fastening to the thicker

My priority over the next few days is getting the coal stove hooked up first.

Winter's coming.